This patent application relates generally to a new and improved, light-weight, fluid-driven, high-powered rescue tool and, specifically, to a new and improved system for driving the rescue tool.
High powered rescue tools are shown in U.S. Pat. Nos. 3,819,153, 4,896,862, 4,531,289, and 4,973,028. They are typically used to extricate victims from metal enclosures, such as automobiles, buses, trucks, elevators, airplanes, trains, and other devices involved in accidents. In addition, rescue tools are used to extricate victims from collapsed concrete and steel structures due to natural disasters, such as earthquakes.
To accomplish successful rescues, several types of rescue tools have been developed, including tools known as spreaders, cutters, and rams. The present invention relates to spreader rescue tools. Spreader tools generally include a pair of spreader arms, a fluid cylinder, and a support structure or housing. The spreader arms are pivotally attached to the housing in a manner that allows them to rotate about pivot points in response to the extension of a fluid cylinder piston rod.
Spreader tools are ordinarily used in two ways. First, they are used to separate or spread the entrapping device that has trapped the victim. To do this, the spreader arms are inserted, in a closed position in which the ends or working portions of the spreader arms are in contact with each other, into a gap or opening that is either present in the device or created by another rescue tool. The spreader arms are then rotated about their respective pivot points to separate, or spread, the working portions from each other, thereby creating an opening in the entrapping device through which the victim can be removed or, at least, removal can be facilitated. The working portions of the spreader arms ordinarily separate to distances of approximately thirty inches to create openings sufficient to effectuate removal of victims.
The second way spreader tools are used is to compress the entrapping device. This is accomplished by reversing the procedure described above. That is, the entrapping device is placed between the open spreader arms which are then rotated about their respective pivot points to close, or bring together the working portions, thereby compressing or crushing the entrapping device.
Various forms of drive mechanisms have previously been employed to rotate the spreader arms about their respective pivot points to separate the working portions to the desired distances. For example, U.S. Pat. No. 3,819,153 discloses a drive system whereby the spreader arms are pivotally connected through drive linkages to a piston rod which, when extended, pushes the spreader arms to rotate about a fixed pivot point. Alternatively, the piston rod has been pivotally attached directly to the spreader arms, allowing the spreader arms to rotate about a moveable pivot point which is connected to a housing through pivoting linkages, as shown in U.S. Pat. No. 4,392,263. Further, rack and pinion drive systems have been utilized to rotate the spreader arms. In some instances the pinion gear has been incorporated into the spreader arm while the rack has been attached to a piston rod of a hydraulic cylinder, thereby causing the working portions to spread in response to extension of the piston rod.
In each of the drive systems discussed above, the spreading force generated at the working portions is greatest when the working portions approach their maximum separation distance, or about 30 inches. However, the range of separation distance most commonly used for this type of rescue tool is the first ten inches of spreader arm separation. Moreover, in practical application, the greatest working tip spreading forces are required at the start of the spreading function when the resistance of the entrapping device to spreading is at its highest level.